There is an increasing reliance on the use of survey data by all sorts of business and political entities. For example, manufacturers of mearly any consumer commodity rely heavily on survey data to advise them whether the products being manufactured by them meet criteria established by the general buying public, which criteria may change from time to time. Political parties are parricularly dependent on survey data for determination of policy.
Surveys may be used, as well, to determine whether a specific individual who responds to a survey may receive one or a number of promotional discount coupons, for example, depending on the pattern of responses that he has made to a given survey. Surveys may also be utilized by service organizations and governments to determine the demand for any specific service to be provided to the public, and so on.
The present invention, while discussed hereafter generally in respect of surveys, is directed to an apparatus for reading and analysing any mark responsive pre-printed form. Such forms may be order forms of all sorts or consumer response forms. One widespread use of forms is in educational testing, using multiple choice forms. Another widespread use of pre-printed forms having a plurality of fields, each with multiple choices, is for purposed of inventory control.
Generally, the pre-printed forms have had to be very specific in terms of their set up, and may indeed require the use of particular markers such as a soft pencil with an entire block being filled by the respondent to indicate his response to any particular question. Such pre-printed forms have generally, in the past, been rather unforgiving as to the inaccuracy of placement by the respondent of his mark indicating his response or answer to any given question, with the result that the survey data may be inaccurate or the analysis of the survey may require human intervention to determine whether an apparent answer is really to be intended.
Other problems that occur in previous mark reading devices and methods are the inability of the prior art devices to permit or make adjustments for rotational displacement (within limits) and/or horizontal or vertical alignment problems (within limits). Often, especially when the prior art device requires use of an optical character reader, there are very tight tolerances for paper placement in the machine for analysing the response, and for placement of the responses on the paper in very tightly defined areas.
In general, the present invention overcomes a number of problems of the prior art by providing an apparatus that may utilize a plurality of video cameras, where each camera may review only a portion of a respose page. A plurality of computer may be used, which permits a faster analysis of a plurality of survey forms--which may, in some circumstancs, amount to an analysis of thousands or hundreds of thousnds of individual documents. The use of a plurality of cameras removes any restrictions or constraints as to the size of the pre-printed form--that is, th size of the form is virtually unlimited, the constraint being imposed on the paper handling apparatus that will be used when the forms are read and analysed in keeping with the present invention. Moreover, the use of a plurality of cameras permits for a higher pixel density, thereby assuring greater certainty of mark analysis, and as well allowing for a greater packing density of responses--more response positions per page.
Compensation may be provided for scaling, that is for allowances of size of the pre-printed form, within limits. Sometimes, survey forms may be photocopied, and the size of the copy may vary by as much as two percent or more from the original. Moreover, pre-printed forms may be printed on various grades of paper under various relative humidity conditions, and humidity conditions may change over the period of time when the survey results are being analysed, each such condition having some effect on the physical size of the page.
With the present invention, a plurality of templates may be set up, one for each video camera which is used to review a page of a survey form, and a plurality of groups of templates may be set up to accommodate for multi-page survey forms. In other words, a particular survey may have one, two, four, or more, pages, and templates may be set up so that all that is required is certain physical handling to ensure that the pages that are presented to the apparatus are in the order that the apparatus expects them. Indeed, by matching templates against an image of a document being analysed, and determining a gross mis-match, the apparatus and methods according to the present invention will intercede and signal to the operator that perhaps the wrong form is being used. On the other hand, on certain advances of the present invention, rotational displacement in multiples of 90.degree. might be accommodated, but more usually all survey forms are stacked in the same displacement so as to speed up the analysis of the documents.
The methods provided by the present invention may be carried out on a number of different kinds and complexities of apparatus. In general, the present invention provides a method of optically reading a pre-printed page so as to determine the presence or absence of marked responses on that page in pre-designated positions, where the pre-designation of those positions is not otherwise a factor. In other words, anywhere on the page there may a pre-designated position for a response, and the present invention will provide for determination as to whether there is a mark in that position on the survey form being reviewed.
The invention calls for the steps of:
placing the pre-printed page in the field of a video camera, viewing the pre-printed page, making a digitized image of the pre-printed page, and storing the digital values of the digitized image in a computer memory;
imposing on the digitized image data of the pre-printed page data, further data describing at least two horizontal reference lines and at least two vertical reference lines that are spaced apart vertically and horizontally, respectively, so as to set up a reference frame, for which reference frame relative response positions are to be examined for the presence or absence or marked responses;
imposing on the digitized image data, further data describing at least a first landmark position relative to said reference frame, where said first landmark position is at a place on the pr-printed page relative to the said reference frame where a pre-printed mark is always to be found;
imposing on the digitized image data, further data describing at least a first whitespace position which is at a place on the pre-printed page relative to said reference frame where a mark is never expected to be found; thereby establishing for the pre-printed page absolute references to allow determination of the presence and absence, respectively, of markings on said page;
imposing on said digitized image data, further data describing a reference for every response position relative to said reference frame, where the presence or absence of responses on said pre-printed page are to be determined;
writing all the reference line, landmark, whitespace, and response position data, to a computer template data file;
repeating the above steps for as many video cameras as are to be used for optically reading said pre-printed page;
establishing analysis algorithms for determining the presence or absence of a mark at each response position, so that by comparing the digital value of the signal read at each response position with the digital values of the landmark and whitespace data, the presence or absence of a mark at each response position may be determined;
and thereafter, placing a marked pre-printed page in the field of said at least one video camera, digitizing the image from said at least one video camera and comparing it to the template data file for expected response and confirmation that the reference frame is found; and when the reference frame is found, determining the presence or absence of a mark in each response position by using such algorithms as may be necessary for such determination;
repeating the above steps for as many video cameras as are to by used for optically reading said pre-printed page;
capturing and writing to a computer data file, the data for all responses noted on the pre-printed page; and
repeating the above digitizing, comparing, algorithm analysis, and data capture steps, for as many pre-printed pages as there are to be optically read and analysed.
Other steps may particularly be followed, as noted hereafter, to enhance or speed up or otherwise optimise the analysis of a plurallity of pre-printed pages having survey data marked thereon.